The present invention is related to a multipartitioned data processing system and is more particularly related to non-disruptive recovery of a single partition in a multipartitioned data processing system.
A host Fibre Channel adapter supporting multiple logical partitions (LPARs) often requires multiple Fibre Channel addresses (N_Port IDs). An example of a configuration requiring the adapter to have multiple N_Port IDs is when the adapter is shared by multiple LPARs executing the SCSI/Fibre Channel Protocol (FCP). While methods for obtaining multiple N Port IDs have recently been developed, there is no existing method by which a specific N Port ID may be removed. The only way to remove an N_Port ID corresponding to a given LPAR is to remove all N_Port IDs for all LPARs.
This situation is undesirable because error-recovery actions for errors relating to a given LPAR often require removal and re-initialization of the N_Port ID corresponding to that LPAR. Since the only way to reinitialize the N_Port ID corresponding to the faulted LPAR is to remove all LPAR IDs, then error-recovery actions for a given LPAR disrupt ongoing operations in all other LPARs which are sharing the adapter. A method is needed which can remove the N_Port ID of a given LPAR without affecting ongoing operations in other LPARs.
Currently, the Logout (LOGO) Extended Link Service (ELS) command is only sent to other (remote) N_Ports; it is not sent to the fabric port (F_Port). This allows a host adapter to log out with a remote N_Port (for situations such as error-recovery), but it does not allow the host adapter to log out with the fabric. In order to log out with the fabric F_Port, link-level primitive sequences are currently required. These primitive sequences not only log out the attached N_Port, but they also reinitialize the synchronization on the link. This may be acceptable for configurations in which the host adapter has only a single N_Port ID, but in cases where the adapter has multiple N_Port IDs, it results in logging out all N_Port IDs for the host adapter.
Currently, most single host adapters do not have more than one N_Port ID; therefore, there has been no need to remove one N_Port ID without affecting other N Port IDs assigned to the adapter.
One alternative to the present invention where a single host adapter does support more than one N_Port ID is to require the adapter to de-register one of its N_Port_IDs from the fabric name-server database. This alternative would require the fabric to provide a name-server which communicates with the fabric F_Port in order to notify the fabric that the N_Port ID had been removed. Requiring the presence of a name server function in the fabric is costly and it requires communication code within the Fibre Channel.
U.S. Pat. No. 5,276,813 issued Jan. 4, 1994 to Elliott et al. for ACQUIRING ADDRESSES IN AN INPUT/OUTPUT SYSTEM, discloses a computer Input/Output system in which link-level facilities issue an acquire link address frame when initially coming on line. A dynamic switch receiving the frame then assigns a link address to the link-level facility.
U.S. Pat. No. 5,420,988 issued May 30, 1995 to Elliott for ESTABLISHING LOGICAL PATHS THROUGH A SWITCH BETWEEN CHANNEL AND CONTROL UNITS IN A COMPUTER I/O SYSTEM, discloses a mechanism for assigning multiple logical path identifications with a single physical path.
U.S. Pat. No. 6,084,859 issued Jul. 4, 2000 to Ratcliff et al. for INTERNET PROTOCOL ASSISTS USING MULTI-PATH CHANNEL PROTOCOL, discloses an apparatus for allowing any initiating host to establish communications with any receiving host in a computing network using a multi-path channel communication protocol.